Dystrophic epidermolysis bullosa (DEB) is an inherited mechanobullous disorder characterized by fragility of the skin and mucous membranes. The morphological hallmark of DEB includes splitting of the basement membrane zone of the dermal-epidermal junction, with a cleavage plane lying within the papillary dermis. The abnormal assembly of anchoring fibrils is caused by genetic mutations in the gene (COL7A1) encoding collagen type VII synthesized by the basal keratinocytes of the epithelium and the fibroblast of the papillary dermis. At present, there are no specific therapies for any form of inherited DEB. Day-to-day management of the disease is concentrated on the prevention of mechanical trauma, infections via judicious use of bandages or loose-fitting garments and topical antibiotics. Precise understanding of the genetic lesions underlying different subtypes of DEB, and elucidation of the consequences of such mutations at the protein level, enabled us to continue our attempts to develop therapy approaches towards counteracting the clinical manifestations in this devastating skin disease. Recent advances in stem cell research have raised the possibility that use of adult stem cells from bone marrow may provide dramatic new therapies for treatment of inherited and acquired diseases. Bone marrow contains mesenchymal progenitor cells, called mesenchymal stem cells (MSC), that have several unique properties suggesting the feasibility of their use as a therapeutic vehicle: (1) a relatively simple isolation;(2) the ability to be cultured in vitro in minimal conditions and to expand to quantities required for therapy;(3) the ability for ex vivo transduction;(4) plasticity, the potential to differentiate under exogenous stimuli;(5) the ability to engraft after reintroduction;(6) high metabolic activity and efficient machinery to express therapeutic proteins in secretory form;and, (7) the ability to be delivered systematically or locally. The proposed research is a logistical extension of our work in the field of non-viral gene therapy. The main objective of these studies is to test the hypothesis that engraftment of genetically normal MSC will lead to expansion of the transplanted cells in sufficient numbers in the skin of DEB mice and the level of collagen VII will be sufficient to reduce the pathologic phenotype. The following parameters are will be investigated: (1) the rout of MSC delivery, distribution and quantity of transplanted cells in DEB skin;(2) the kinetics of MSC distribution in DEB skin;(3) the phenotypic and functional features of engrafted MSC;(4) the kinetics of distribution and release of mature collagen VII in the intact mouse skin;(5) the ability of MSC to produce collagen VII to form anchoring fibril-like structures;(6) the deposition of collagen VII fibers into the BMZ;(7) the structure of the newly formed collagen VII fibers;and, (8) the ability of newly formed fibers to interact with BMZ's macromolecules. A successful outcome of these studies may form a platform for development of a novel therapeutic approach for curing connective tissue disorders, as well as other human genetic disorders. In the current project, we suggested to test the hypothesis that engraftment of genetically normal mesenchymal stem cells isolated from bone marrow will lead to expansion of transplanted cells in sufficient numbers in the affected skin of DEB mice and the level of collagen VII will be sufficient to reduce the pathologic phenotype. If successful, the suggested strategy may become powerful therapeutic approach for treatment of connective tissue disorders, in particular dystrophic epidermolysis bullosa, and benefit public health.